Power supply apparatus for electrostatic charging and method for same

ABSTRACT

A power supply apparatus for electrostatic charging sprayed liquids from a spraying apparatus and method for same, the apparatus including a rotor having a magnet and magnetic poles, a booster coil assembly facing the rotor, for inducing high voltage AC pulses during the rotation of the rotor, and a rectifier for rectifying the high voltage AC pulses induced by the booster coil assembly to high voltage DC pulses and for supplying the high voltage DC pulses to a charging electrode. The power supply apparatus provides a compact and lightweight power generator system, thus eliminating cumbersome operations such as replacement or recharging of a large battery. In addition, a lighter weight and simplified operation reduces the burden on users and facilitates more efficient spraying.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to devices that useelectrostatic charging, such as an electrostatic sprayer for sprayingliquid chemicals, paint, etc. charged with static electricity. Morespecifically, the present invention relates to a power supply apparatusthat supplies high voltage DC (direct current) pulses to a chargingelectrode, and to a method for supplying power for electrostaticcharging.

2. Description of the Related Art

As is known in the art, a typical electrostatic sprayer has a spraynozzle including, for example, a high-potential annular electrodedisposed downstream thereof. Using the charging electrode, thisconventional electrostatic sprayer electrostatically charges liquidssuch as chemicals as they are sprayed. The charged, sprayed chemicalsadhere well to agricultural crops and the like, and provide the improvedeffectiveness of bactericide, insecticide, etc.

The typical electrostatic sprayer is generally used in the field, andfor this purpose employs a portable battery as a power supply for thesprayer. In operation, a DC (direct current) voltage of this battery isboosted, and is then continuously applied to the annular electrodeserving as a charging electrode positioned in the vicinity of the spraynozzle.

However, the typical electrostatic sprayer suffers from severaldrawbacks. For instance, the typical electrostatic sprayer requires alarge battery and includes complicated, expensive electric circuits anddevices to boost a battery voltage. In addition, a constant high voltagedirect current must be continuously supplied to the electrode, whichplaces a high load on the battery and drains the battery charge quickly.Thus, frequent replacement or recharging of the large battery isrequired. Further, the heavy weight of the battery makes a handheld orshoulder-type electrostatic sprayer bulky and less maneuverable. In theend, the heavy weight exhausts the operator and renders applicationprocedures less efficient overall.

SUMMARY OF THE INVENTION

In light of the foregoing problems, the present invention provides apower supply apparatus for electrostatic charging which is suitable foruse in a handheld device that uses electrostatic charging, such as anelectrostatic sprayer or similar device. The power supply apparatusproduces a pulsed DC high voltage, thereby remarkably reducing a load onthe power supply. Further, to operate, for example, a pump in thesprayer, the power supply apparatus uses a compact and lightweight powergenerator system, such as power generator systems of an igniter for aninternal combustion engine. As a result, the present invention uses asmall battery and, thus, eliminates cumbersome operations such as thereplacement and recharging of a large battery. In addition, the presentinvention reduces the burden on a user and makes spraying moreefficient.

In one aspect of the present invention, a power supply apparatus forelectrostatic charging According to the present invention supplies highvoltage DC pulses to a charging electrode.

In another aspect, a power supply apparatus for electrostatic chargingAccording to the present invention includes a rotor having a magnet andmagnetic poles, a booster facing the rotor, for inducing high voltage AC(alternating current) pulses during rotation of the rotor, and arectifier for rectifying the high voltage AC pulses induced by thebooster to high voltage DC pulses and for supplying the high voltage DCpulses to a charging electrode. With these features, the power supplyapparatus of the present invention provides a compact and lightweightpower generator system that eliminates the need for a large battery andthe associated cumbersome replacement and recharging operations. Inaddition, the present invention reduces the physical burden on theoperator and improves work efficiency.

According to a preferred embodiment of the present invention, therectifier comprises a high voltage diode or diodes, for the half-wave orfull-wave rectifying of the high voltage AC pulses induced by thebooster. The high voltage diode may be used to convert high voltage ACpulses to high voltage DC pulses, enabling the resulting high voltage DCto be supplied to the charging electrode in a stable manner.

According to a preferred embodiment of the present invention, the rotoris driven by an internal combustion engine. As such, the rotor of thepower supply apparatus faces an ignition coil assembly of an igniter ofthe internal combustion engine. As the rotor turns and the magnet andmagnetic poles pass the ignition coil assembly, the ignition coilassembly generates high voltage pulses and supplies the pulses to anignition plug of the internal combustion engine. Thus, conventionalinternal combustion engines can be easily adapted to operate the powersupply apparatus of the present invention. For example, in an internalcombustion engine that drives a liquid chemical pump, the igniter rotorof the engine may be conveniently used to supply a predetermined powerto a charging electrode.

Therefore, the power supply apparatus of the present invention, using apulsed high voltage, remarkably reduces consumption of electric power ascompared to a conventional constant voltage power supply.

Accordingly, an object of the present invention is to provide a compactand lightweight power supply apparatus for handheld devices that useelectrostatic charging, such as portable electrostatic chemicalsprayers.

Another object of the present invention is to provide an electrostaticcharging power supply apparatus that can be driven by an internalcombustion engine.

Another object of the present invention is to provide a power supplyapparatus that supplies high voltage DC pulses to a charging electrode.

These and other objects of the present invention are described in detailin the detailed description of the invention, the appended drawings, andthe attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic circuit diagram of a power supply apparatus in anelectrostatic sprayer According to one preferred embodiment of thepresent invention;

FIG. 2 is a waveform diagram of voltage pulses generated by the boostercoil assembly shown in FIG. 1;

FIG. 3 is a waveform diagram of high voltage pulses rectified by thehigh voltage diode shown in FIG. 1;

FIG. 4 is a schematic circuit diagram of a power supply apparatusAccording to another preferred embodiment of the present invention;

FIG. 5 is a waveform diagram of a possible voltage to be supplied to thecharging electrode shown in FIG. 1; and

FIG. 6 is a waveform diagram of another possible voltage to be suppliedto the charging electrode shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, preferred embodiments of the present invention will be describedwith reference to the Accompanying drawings.

FIG. 1 is a schematic circuit diagram of a power supply apparatusAccording to one preferred embodiment of the present invention. In FIG.1, According to this preferred embodiment, a rotor 1 is mounted to acrankshaft 2 of an air-cooled 2-cycle gasoline engine (not shown). Theengine drives the crankshaft 2, which, in turn, rotates the rotor 1. Therotor 1 is used in an igniter for an internal combustion engine in apower sprayer. In this preferred embodiment, the power sprayer has awell known structure in which a pump 12 pumps liquid chemicals into aspray nozzle 13.

The rotor 1 is a disc made of non-magnetic material such as aluminumalloy. Embedded in the rotor 1 are a magnet 3 and two magnetic poles 4that sandwich the magnet 3 therebetween. Having ignition coils used as abooster coil assembly, ignition coil assembly 5 is arranged close to therotor 1, such that the ignition coil assembly 5 and the rotor 1 are incommunication, e.g., magnetic communication. The ignition coil assembly5 induces a pulsed high voltage in response to magnetic flux of themagnet 3 while the rotor 1 rotates. Each of the ignition coils is woundaround a U-shaped core 6.

Connected to the ignition coil assembly 5 is an ignition plug 7 of theinternal combustion engine. The ignition plug 7 produces sparks inresponse to high voltage pulses from the ignition coil assembly 5. Thesparks ignite fuel in a cylinder. In turn, the internal combustionengine commences operation and/or continuously operates to drive thepump 12.

In the power supply apparatus shown in FIG. 1, the ignition coilassembly 5 generates high voltage AC pulses that are supplied to theignition plug 7. Optionally, however, a magneto type igniter havingwell-known ignition coils or an ignition coil unit, or others such as abattery-ignition type igniter, may be used equally well. The highvoltage ignition pulses may be produced by means of any circuit system,such as a capacitor discharge ignition (CDI) or a transistor controlledignition (TCI).

A booster coil assembly 8 having booster coils is further arranged closeto the rotor 1, such that the booster coil assembly 8 and the rotor 1are in communication, e.g., magnetic communication. As the rotor 1rotates upon Actuation of the internal combustion engine, each time themagnet 3 and the magnetic poles 4 pass by the booster coil assembly 8,the booster coil assembly 8 (of which each booster coil is wound arounda core 9) generates a high voltage AC pulse.

Booster coil assembly 8 is connected to a charging electrode 11 via ahigh voltage diode 10. The arrangement is such that the cathode of thehigh voltage diode 10 is connected to a charging electrode 11 as shownin FIG. 1 when the leading edge of the voltage pulses generated by thebooster coil assembly 8 rises. Conversely, when the leading edge of thegenerated voltage pulses falls, the anode of the high voltage diode 10is connected to the charging electrode 11. The charging electrode 11 canbe supplied with high voltage DC pulses (P) on the order of 10 kV to 15kV.

In operation, initially, the rotor 1 is rotated manually or by using acell starter or the like. The magnet 3 and the magnetic poles 4, inpassing by the ignition coil assembly 5, induce high voltage AC pulsesin the ignition coil assembly 5. The resulting AC pulses cause theignition plug 7 of the internal combustion engine to produce a dischargespark, so that fuel in the cylinder is ignited. This ignition procedureis repeated, and the internal combustion engine continues to operate.Along with the operation of the internal combustion engine, the rotor 1continuously rotates.

During the rotation of the rotor 1, high voltage AC pulses depicted inFIG. 2 are consecutively induced in the booster coil assembly 8positioned near the rotor 1. The resulting AC pulses are rectified (inFIG. 2, half-wave rectification is performed) by the high voltage diode10 to high voltage DC pulses P depicted in FIG. 3, which are thensupplied to the charging electrode 11. Therefore, by means of the pump12 operated by the internal combustion engine, the liquid chemicalssprayed from the spray nozzle 13 can be charged with static electricitybefore being sprayed. In other words, electric power for effecting theelectrostatic charging is derived from the internal combustion enginethat drives the pump 12.

FIG. 4 shows another preferred embodiment in which a battery-basedigniter is employed. The same and corresponding components as those inthe previous embodiment are designated by the same reference numerals.

According to this embodiment, a compact and small-capacity battery 112is used as a power supply for starting an internal combustion engine. Avoltage of the power supply is boosted by an ignition circuit 113, andis then distributed to an ignition coil assembly 5A for the internalcombustion engine.

In this embodiment, once the internal combustion engine is started, boththe ignition pulses to be supplied to the ignition plug 7 and the highvoltage pulses to be supplied to the charging electrode 11 are derivedfrom the ignition circuit 113.

The rotation of the crankshaft 2 of the internal combustion engineallows electric power to be continuously supplied to the electrostaticsprayer. This continuous power supply eliminates the need for a largeheavy battery, making the present invention more convenient to transportand less tiring to an operator. This configuration also reduces theoverall cost of the device by eliminating the booster circuit used inthe conventional device, which includes an expensive and complexinverter.

The high voltage AC pulses produced by the booster coil assembly 8 or 8Aform waves as shown in FIG. 2, in a period of one rotation of the rotor1. Alternatively, a square wave generator, such as a knownmulti-vibrator, may be used to generate square wave pulses as depictedin FIG. 5. Or, alternatively, an integral circuit may be used to formtriangular wave pulses as depicted in FIG. 6. The charging electrode 11may be supplied with such pulses.

In FIG. 1, a single high voltage diode 10 Acting as a rectifier isconnected between the booster coil assembly 8 and the charging electrode11. Instead of this configuration, alternately, a full-wave rectifyingcircuit having four high voltage diodes bridged to one another may beconnected therebetween, as appropriate. Otherwise, a smoothing capacitormay be connected to these components if necessary.

Although the invention has been described through illustration of itspreferred forms, it is to be understood that the described embodimentsare only illustrative and that various changes and modifications may beimparted thereto without departing from the scope of the presentinvention, which is limited solely by the appended claims.

What is claimed is:
 1. A power supply apparatus for electrostaticcharging an electrode in an electrostatic spraying apparatus, the powersupply apparatus comprising: (a) a rotor; (b) a magnet and magneticpoles embedded in the rotor, the magnet positioned between the magneticpoles; (c) a booster coil assembly in communication with the magnet andthe magnetic poles of the rotor; (d) a rectifier connected to thebooster coil assembly; (e) a charging electrode connected to therectifier, the charging electrode configured to electrostatically chargeliquid at the time of spraying; and (f) a crankshaft on which the rotoris mounted, the crankshaft being driven by an internal combustionengine, wherein the sprayed liquid is a liquid that is different fromany liquid employed to operate the internal combustion engine.
 2. Thepower supply apparatus of claim 1, wherein the booster coil assemblygenerates high voltage AC pulses as the magnet and magnetic poles of therotor pass by the booster coil assembly.
 3. The power supply apparatusof claim 2, wherein the booster coil assembly generates one of wavepulses, square wave pulses, and triangular wave pulses.
 4. The powersupply apparatus of claim 2, wherein the rectifier rectifies the highvoltage AC pulses to high voltage DC pulses that are supplied to thecharging electrode.
 5. The power supply apparatus of claim 2, whereinthe rectifier is a diode having a cathode and an anode, wherein thecathode is connected to the charging electrode when a leading edge ofthe high voltage AC pulses rises, and wherein the anode is connected tothe charging electrode when the leading edge of the high voltage ACpulses falls.
 6. The power supply apparatus of claim 1, wherein thecharging electrode is supplied with high voltage DC pulses.
 7. The powersupply apparatus of claim 6, wherein the high voltage DC pulses are onthe order of 10 kV to 15 kV.
 8. The power supply apparatus of claim 1,wherein the rectifier is a full-wave rectifying circuit having diodesbridged to each other.
 9. The power supply of claim 1, furthercomprising: (g) an ignition coil assembly in communication with therotor, the ignition coil assembly generating high voltage AC pulses asthe magnet and magnetic poles of the rotor pass by the ignition coilassembly; and (h) an ignition plug in communication with the ignitioncoil, the ignition plug producing sparks in response to the high voltageAC pulses received from the ignition coil assembly.
 10. The power supplyapparatus of claim 9, further comprising: (i) a pump driven by theinternal combustion engine; and (j) a spray nozzle in fluidcommunication with the pump and positioned near the charging electrodesuch that fluids exiting the spray nozzle are charged with staticelectricity.
 11. The power supply apparatus of claim 9, furthercomprising: (i) a battery for starting the internal combustion engine;and (j) an ignition circuit that boosts a voltage supplied by thebattery and distributes the voltage to the ignition coil assembly, andwherein, when the internal combustion engine is running, the highvoltage AC pulses supplied to the ignition plug and high voltage DCpulses supplied to the charging electrode derive from the ignitioncircuit.
 12. The power supply apparatus of claim 11, wherein the rotoris mounted on a crankshaft of an air-cooled 2-cycle gasoline engine. 13.A power supply apparatus, which is itself powered by an internalcombustion engine, for electrostatic charging an electrode configured toelectrostatically charge sprayed liquids comprising: (a) a booster thatgenerates high voltage AC pulses; (b) a rectifier in communication withthe booster, wherein the rectifier receives the high voltage AC pulsesand rectifies the high voltage AC pulses to high voltage DC pulses; and(c) a charging electrode in communication with the rectifier, whereinthe charging electrode receives the high voltage DC pulses and whereinthe charging electrode is configured to electrostatically charge sprayedliquids, wherein the sprayed liquids are liquids that are different fromliquids employed to operate the internal combustion engine.
 14. A powersupply apparatus for electrostatic charging a liquid that is sprayedfrom a spraying apparatus, the power supply apparatus comprising: (a) arotor having a magnet and magnetic poles; (b) a booster in communicationwith the rotor, wherein the booster generates high voltage AC pulsesduring rotation of the rotor; and (c) a rectifier that rectifies thehigh voltage AC pulses to high voltage DC pulses and supplies the highvoltage DC pulses to a charging electrode, wherein the chargingelectrode is configured to electrostatically charge a liquid that issprayed from the spraying apparatus, wherein an internal combustionengine operates the rotor and wherein the liquid that is sprayed isdifferent from any liquid employed to operate the internal combustionengine.
 15. The power supply apparatus of claim 14, wherein therectifier comprises a high voltage diode for full-wave rectifying of thehigh voltage AC pulses.
 16. The power supply apparatus of claim 14,wherein the rectifier comprises a high voltage diode for half-waverectifying of the high voltage AC pulses.
 17. The power supply apparatusof claim 14, wherein the internal combustion engine comprising: (i) anigniter having an ignition coil, wherein the rotor is in communicationwith the ignition coil and the ignition coil induces high voltagepulses; and (ii) an ignition plug that receives the high voltage pulsesfrom the ignition coil.
 18. A method for supplying power for charging anelectrode configured to electrostatically charge sprayed particles, themethod comprising: rotating a rotor near a booster coil assembly, therotor having magnets and magnetic poles; inducing high voltage AC pulsesin the booster coil assembly; rectifying the high voltage AC pulses tohigh voltage DC pulses; supplying the high voltage DC pulses to acharging electrode; pumping a liquid through a spray nozzle;electrostatically charging the liquid with the electrode that issupplied with high voltage DC pulses; and mounting the rotor on acrankshaft of an internal combustion engine wherein the liquid that ispumped through the spray nozzle is different from any liquid employed tooperate the internal combustion engine.
 19. The method of claim 18,wherein the step of rotating the rotor comprises: rotating the rotornear an ignition coil assembly; inducing high voltage AC pulses in theignition coil assembly; supplying the high voltage AC pulses of theignition coil assembly to an ignition plug; and producing sparks withthe ignition plug that ignite fuel, drive the internal combustionengine, and turn the crankshaft and rotor.